Since the invention of the integrated circuit, the semiconductor industry has experienced rapid growth due to continuous improvements in the integration density of a variety of electronic components (e.g., transistors, diodes, resistors, capacitors, etc.). For the most part, this improvement in integration density has come from repeated reductions in minimum feature size, which allows more components to be integrated into a given area.
As semiconductor technologies evolve, three dimensional (3D) integrated circuits (ICs) emerge as an effective alternative to further reduce the physical size of a semiconductor chip. In a 3D IC based semiconductor chip, active circuits are fabricated on different wafers and each wafer die is stacked on top of another wafer die using pick-and-place techniques. Much higher density can be achieved by employing 3D IC. Furthermore, 3D ICs can achieve smaller form factors, cost-effectiveness, increased performance and lower power consumption.
A 3D IC device may comprise a top active circuit layer, a bottom active circuit layer and a plurality of inter-layers. One of the inter-layers may be an interposer. In a 3D IC, two dies may be bonded together through a plurality of micro bumps. As a result, a variety of active circuit layers may be stacked together in a 3D IC without an interposer. However, interposers in 3D ICs are still widely used because an interposer, as a relatively large silicon layer, can accommodate various wafer dies different in size. More particularly, interposers can bond various wafer dies together by using micro-bumps. Furthermore, by employing an interposer, the complicated thermal distribution issue of a 3D IC can be simplified.
A 3D IC may comprise a variety of semiconductor dies, each of which may generate an excessive amount of heat during normal operation. As a result, excessive amounts of heat may be generated when the variety of semiconductor dies are placed in a high density IC package. The excessive amounts of heat may decrease the thermal performance of the 3D IC.
Corresponding numerals and symbols in the different figures generally refer to corresponding parts unless otherwise indicated. The figures are drawn to clearly illustrate the relevant aspects of the various embodiments and are not necessarily drawn to scale.